Apparatus and method for scheduling packets

ABSTRACT

An apparatus comprising a controller for controlling radio communication using communication resources for user data communication, and control resources for controlling communication on the communication resources, an allocator for allocating mobile stations to use at least one of a dynamic allocation and a persistent allocation, each allocation defining a different utilization of the control resources and communication resources, a monitor for monitoring one or more reallocation conditions associated with at least one of the dynamic allocation and the persistent allocation, and a reallocator configured to reallocate at least one mobile station if one of the one or more reallocation conditions is fulfilled.

FIELD OF THE INVENTION

The invention relates to an apparatus, a method, and a computer programproduct for scheduling packets.

BACKGROUND OF THE INVENTION

In Voice over Internet Protocol (VoIP) in radio communication systems,the principal packet scheduling is fully dynamic, where each user datapacket is transmitted with associated control signaling. Fully dynamicpacket scheduling is able to fully exploit time and frequency domainscheduling gains with the cost of increased control signaling. Thisincreased control overhead may limit system performance with e.g. VoIPtype of traffic, where the size of the transmitted packet is rathersmall. This, together with strict delay requirements of VoIP traffic,implies that the maximum number of simultaneously scheduled users, givenby the number of control channels, is not sufficient to fill theresources available for user data transmission. Thus, part of thetransmission resources may be left unused and part of the systemcapacity may be wasted.

SUMMARY OF THE INVENTION

In one aspect, there is provided an apparatus comprising a controllerconfigured to provide radio communication using communication resourcesfor user data communication, and control resources for indicatingallocation of the communication resources, an allocator configured toallocate mobile stations to use at least one of a dynamic allocation anda persistent allocation, each allocation defining a differentutilization of the control resources and communication resources, amonitor configured to monitor one or more reallocation conditionsassociated with at least one of the dynamic allocation and thepersistent allocation, and a reallocator configured to reallocate atleast one mobile station if one of the one or more reallocationconditions is fulfilled.

In another aspect, there is provided an apparatus comprising means forproviding radio communication using communication resources for userdata communication, and control resources for indicating allocation ofthe communication resources, means for allocating mobile stations to useat least one of a dynamic allocation and a persistent allocation, eachallocation defining a different utilization of the control resources andcommunication resources, means for monitoring one or more reallocationconditions associated with at least one of the dynamic allocation andthe persistent allocation, and means for reallocating at least onemobile station if one of the one or more reallocation conditions isfulfilled.

In still another aspect, there is provided a method comprising providingcommunication in a radio system, including communication resources foruser data communication, and control resources for indicating allocationof the communication resources, allocating mobile stations to use atleast one of a dynamic allocation and a persistent allocation, eachallocation defining a different utilization of the control resources andcommunication resources, monitoring one or more reallocation conditionsassociated with at least one of the dynamic allocation and thepersistent allocation, and reallocating at least one mobile station ifone of the one or more reallocation conditions is fulfilled.

In still another aspect, there is provided a computer-readable storagemedium encoded with instructions that, when executed by a computer,perform providing communication in a radio system, includingcommunication resources for user data communication, and controlresources for indicating allocation of the communication resources,allocating mobile stations to use at least one of a dynamic allocationand a persistent allocation, each allocation defining a differentutilization of the control resources and communication resources,monitoring one or more reallocation conditions associated with at leastone of the dynamic allocation and the persistent allocation, andreallocating at least one mobile station if one of the one or morereallocation conditions is fulfilled.

DRAWINGS

In the following, the invention will be described in greater detail bymeans of preferred embodiments with reference to the accompanyingdrawings, in which

FIG. 1 shows an embodiment of a radio system;

FIG. 2 shows an embodiment of a method; and

FIG. 3 shows an embodiment of a radio system.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows an embodiment of a radio system. The radio system may be a3GPP LTE (Long Term Evolution) radio system, for instance. LTE is herementioned only as an example and the embodiments may be applied to otherradio systems as well. As another example, the embodiments may beapplied to a HSDPA (High Speed Downlink Packet Access) radio system, forinstance.

In an embodiment, the invention may be applied to scheduling andallocating of resources for VoIP users. VoIP is here mentioned only asan example, and the embodiments may be applied to any other packet basedtraffic types as well. The resources to be allocated or scheduled may beuplink or downlink communication resources. The resources may, forinstance, be characterized by a combination of frequency and time, suchas in LTE, or by a combination of an OSVF (Orthogonal Variable SpreadingFactor) code and time as in the HSDPA system.

FIG. 1 shows six mobile stations MS_1 to MS_6, which may here be assumedto be VoIP users. The figure also shows two resource groups 104 and 106.The first resource group 104 may include control channel resources, suchas PDCCH (Physical Downlink Control Channel) resources. Each resourcemay be characterized by a combination of frequency and time, forinstance. FIG. 1 also shows a second group of resources 106, which mayinclude communication resources usable for user data communication.These resources may include DSCH (Downlink Shared Channel) resources,for instance, characterized by a combination of time and frequency.

The mobile stations may be grouped to two groups 100 and 102. The group100 is here called a dynamic allocation and the group 102 is called apersistent allocation.

When a user, that is a mobile station, is in the dynamic pool 100, acontrol channel resource from the resource pool 104 and a user dataresource from the user data resource pool 106 may be allocated to theuser. The allocation of the user data resource may be dynamical for eachTTI (transmit time interval). This is highlighted by reference to MS_1(110), which has an allocated control channel resource C1. In a firstTTI, C1 points to a user data resource D3 in the user data resource pool106. In the next TTI, C1 points to another user data resource D2. Thus,for each TTI, C1 may point to a different user data resource, but thisis not necessarily the case but the same resource may be allocated insucceeding TTI's. Furthermore, the control channel resource allocated toa user may be different in succeeding TTI's. That is, in a first TTI, acontrol channel resource C1 may be allocated to a user and in asubsequent second TTI, a control channel resource C2 may be allocated tothe user. Correspondingly, a control channel resource C2 has beenallocated to MS_2 (112), and C3 has been allocated to MS_3 (114). In thedepicted TTI, C2 points to a frequency-time combination illustrated byD4, and C3 points to a frequency-time combination illustrated by D1.

The persistent allocation 102 includes three mobile stations 120 to 124.Persistent allocation means here that a user data resource may be usedby a user without an associated control resource. In an embodiment, auser data resource may be allocated to a user in each TTI. In anotherembodiment, a user data resource may be allocated in each other TTI, forinstance. In the other TTI's, the user may be allocated dynamically, orhave no allocation at all, for instance.

In FIG. 1, each of the mobile stations 120 to 124 has a persistentresource allocated from the resource pool 106. This means that themobile station has a user data resource from pool 106 allocated withoutassociated control signaling. The mobile station may use the sameresource in a plurality of successive TTI's, for instance. Because theresource to be used is known to the mobile station, the mobile stationneeds no resource from the control channel resource pool 104 to be usedfor this indication.

In FIG. 1, MS_4 is shown to a have a persistent resource D7, which is tobe used for user data transmission/reception. For data packetretransmissions and SID transmissions, however, the dynamic approach maybe used. For this purpose, in a certain TTI, C9+D5 may be allocated forMS_4.

FIG. 2 shows an embodiment of a method. The method relates to a radiosystem, such as a packet radio system having user data communicationresources and control channel resources for controlling the datatransmission/reception on the user data communication resources.

In 202 and 204, the users are allocated according to a dynamic or apersistent allocation. Originally, all the users may be allocateddynamically but if the control channel resources come to an end or areabout to come to an end or some other relevant criterion is fulfilled,users may be moved from dynamic to persistent allocation.

In an embodiment, persistent allocation may be applied as a talk-spurtbased scheduling scheme. In the talk-spurt based persistent schedulingscheme, at the beginning of a talk spurt a dedicated time/frequencyresource is persistently allocated for a user from the user dataresource pool. During the persistent allocation, first transmissions ofdata (before retransmissions) may be done without associated controlchannel signaling, no control channel resources need to be allocated forthe user for indicating the allocation of the user data resource for thefirst transmissions. At the end of the talk spurt when a silent periodstarts, the persistently allocated transmission resources are released.Re-transmissions and SID (Silence insertion descriptor) frames may bescheduled dynamically for a user even if the user is allocatedpersistently. Thus, retransmissions may be carried out by using acontrol channel resource and an associated user data channel resource.

The dynamic and persistent packet scheduling methods may be used incombination. A dynamic pool of users scheduled dynamically and apersistent pool of users scheduled in a manner similar to that used withtalk-spurt based scheduling may be maintained.

In an embodiment, a mechanism is provided for moving users from thedynamic to the persistent pool, and vice versa, whenever considerednecessary from point of view of the system performance.

A triggering condition, or a reallocation condition, may be monitoredcontinuously as shown by 206 in FIG. 2. The triggering condition may beassociated with one of the dynamic group or the persistent group or thetriggering conditions of both groups may be monitored continuously.

A triggering condition associated with the dynamic pool may be thenumber of used or unused control channel elements (CCE), for instance.When the triggering condition with regard to the dynamic group isfulfilled, moving a user from the dynamic pool to the persistent poolmay be initiated. A triggering condition associated with the persistentpool may be that the user data transmission resources are coming to anend, or a threshold value depicting the percentage of reserved resourceshas been exceeded. In such a case, moving one or more users to thedynamic pool may be initiated.

Moving one or more users from the dynamic to the persistent pool maytake place whenever a need exists to reduce the number of occupiedcontrol channel elements. In an embodiment, such a need may arise whenthe performance is control channel limited, that is eNodeB measurementsindicate that user data resources are not occupied, that is there areunscheduled frequency resources, but the control channels resources areon average all taken. Furthermore, a need to change a dynamic allocationto a persistent allocation for at least one mobile station may arisewhen users assuming traffic relying on dynamic scheduling (e.g. besteffort (BE) traffic) are entering to the system and some CCE's should bereleased in order to serve such users.

Moving the users from the persistent to the dynamic pool may take placewhen a need exists to optimize user data resource utilization. If userdata resources are mainly occupied, but control overhead is below apredefined limit, it may be beneficial to move one or more users fromthe persistent to the dynamic pool. In this way, it may be possible toutilize transmission resources more efficiently, because the dynamicresource allocation is better from the point of view of user dataresource consumption. In another embodiment, the persistent allocationof a user may turn out to be undesired from the point of view of userQuality of Service (QoS) in that a block error rate (BLER) is too low ortoo high. In still another embodiment, the persistent allocation may benon-optimal due to jitter in VoIP packet arrival, whereby the user failsto use many of the persistent resources. In these cases, a procedure formoving a user back to the dynamic pool might be initiated.

In 208, it is evaluated which group the triggering condition relates to,that is whether the moving of one more mobile stations should be fromthe dynamic to the persistent pool or vice versa. As a simple example, atriggering condition may be a percentage of available/reserved resourcesin comparison to all resources. Thus, for instance, in the case of thedynamic group, a triggering condition may be a predetermined thresholdvalue depicting the percentage of the reserved CCE's with respect to allCCE's. If the percentage of the reserved CCE's exceeds the predeterminedthreshold value, the triggering condition is considered as fulfilled.

If the fulfillment of the triggering condition is associated with thedynamic pool, the method branches to 210 to 218. If the triggeringcondition is associated with the persistent groups, the method branchesto 220 to 228.

The procedure to move users from dynamic to persistent pool aims toreduce the control channel overhead or resource consumption with aminimal increase to the average data resource consumption, which may bemeasured as a Physical Resource Blocks (PRB), for instance. This may beachieved by transferring one or more users from the dynamic to thepersistent pool in such a way that the ratio of the amount of freedcontrol channel resources to the required size of the persistentallocation in RB's, if a user would moved from the dynamic pool to thepersistent pool, is maximized.

First, users in the dynamic pool may be sorted according to 210 in FIG.2 in descending order according to a user-specific metric (1).

$\begin{matrix}{{\chi_{D\; 2P} = {\frac{{SAVINGS\_ IN}{\_ CONTROL}}{{COST\_ IN}{\_ DATA}} = \frac{f\left( S_{cce} \right)}{g\left( C_{RA} \right)}}},} & (1)\end{matrix}$

where ƒ and g are increasing functions on S_(cce) and C_(RA),respectively. Here S_(cce) may denote the achieved savings in controlchannel consumption in terms of CCEs, and C_(RA) may be the cost interms of used user data transmission resources (in terms of RBs), when auser is moved from dynamic to persistent pool.

Savings in control channel consumption, S_(cce), may be defined as adifference O_(CCE) ^(Pers)−O_(CCE) ^(Dyn), where O_(CCE) ^(Pers) andO_(CCE) ^(Dyn) are the estimated number of average consumed controlchannel elements CCEs required for a user for persistent allocation anddynamic scheduling, respectively. The control channel elementconsumption may be per VoIP packet and may include the impact ofretransmissions. eNodeB may estimate these on the basis of the receivedChannel Quality Indicator (CQI) reports and expected BLER of thepersistent allocation, or from the actual realized CCE usage when theuser has been scheduled dynamically.

Similarly, the cost in used transmission resources, C_(RA), may bedefined as the difference RA_(Pers)−RA_(Dyn), where RA_(Pers) is thenumber of virtual/physical resource blocks that would be allocated to auser if moved to the persistent pool, and RA_(Dyn) is the number ofresource blocks per VoIP packet that is on average needed to schedulethe user dynamically.

Although equation (1) illustrates that the metric takes the condition inboth groups into account, the metric may be based on one group only.That is, users may be sorted/ranked on a criterion based on the dynamicor the persistent group only.

When the users are sorted in order of priority/superiority according tothe metric (1), the method may first consider the highest priority userin the sorted list, which is illustrated by 212 in FIG. 2.

In 214, it is checked whether enough transmission resources areavailable to make a persistent resource allocation to the selected user.If this is the case, the user may be moved from a dynamic pool to apersistent pool, and a persistent resource allocation for the user maybe carried out as shown in 216. not enough resources are available forthe first user, the first user is skipped and the procedure is repeatedfor the second user in the list, illustrated by a returning arrow from214 to 212.

Moving of users from the dynamic pool to the persistent pool may berepeated 218 until the whole list has been processed or enough controlchannel resources have been released.

When considering moving users from the persistent pool to the dynamicpool, the aim may be to reduce average PRB consumption of the currentlyserved users, so that more traffic can be sent with the availabletransmission resources. This can be achieved by moving selected usersfrom the persistent pool to the dynamic pool in such a way that theamount of released transmission resources (in terms of RBs) perincreased control channel overhead is maximized.

First, the users in the persistent pool may be sorted 220 in descendingorder according to the metric (2).

$\begin{matrix}{{\chi_{P\; 2D} = {\frac{{SAVINGS\_ IN}{\_ DATA}}{{COST\_ IN}{\_ CONTROL}} = \frac{u\left( S_{RA} \right)}{v\left( C_{CCE} \right)}}},} & (2)\end{matrix}$where u and v are increasing functions on S_(RA) and C_(CCE),respectively. Here S_(RA) denotes the achieved savings in transmissionresource consumption in terms of RBs, and C_(CCE) the cost in terms ofcontrol channel consumption in terms of CCEs, when a user would be movedfrom the dynamic pool to the persistent pool.

The savings in the user data transmission resource consumption, S_(RA),may be defined as the difference RA_(Pers)−RA_(Dyn) whereas the cost incontrol channel consumption, C_(CCE), may be defined as the differenceO_(CCE) ^(Dyn)−O_(CCE) ^(Pers). Here O_(CCE) ^(Pers), O_(CCE) ^(Dyn),RA_(Pers), RA_(Dyn) are as explained above in conjunction with thedynamic-to-persistent metric. When considering moving a user from thepersistent pool to the dynamic pool, the average persistent PRBconsumption may be estimated e.g. from average realized consumption,taking into account also retransmissions, and the dynamic consumptionmay be estimated based on the received CQI information, for instance.Control channel element consumption for both cases may be estimated fromthe realized consumption and the respective BLER estimate derived fromCQI reports.

When the users have been sorted, the highest priority user may first betaken 222 into consideration. It may be checked 224 if enough freecontrol channel resources are available. The estimated number of neededcontrol channel elements for a user may at most be the number of freeCCEs. If enough control channel resources exist, the user may bescheduled dynamically 226, that is moved from the persistent allocationto the dynamic allocation. The persistently allocated transmissionresources of this user may be released and the user may be moved to thedynamic pool. If the amount of control channel resources is notsufficient, the first user is skipped and the above procedure isrepeated for the next user in the list.

Moving of the users from the persistent pool to the dynamic pool may berepeated 228 until the end of the list is faced, until the controlchannel overhead has reached the maximum value, until the controlchannel overhead has reached the maximum value minus some thresholdvalue, which threshold value may be zero, or until enough transmissionresources (in terms of resource blocks) have been released, forinstance.

Although FIG. 2 shows the method steps in succeeding steps, they mayalso be carried out at least partly in parallel, continuously or indifferent order. For instance, a priority order may continuously beprovided for the mobile stations in the dynamic and the persistentallocation. Furthermore, triggering conditions, that is reallocationconditions, may be continuously monitored with respect to theallocations.

FIG. 3 shows an embodiment of a radio system. The radio system includesa radio network NETW 350, and mobile stations MS's 330, 340 having acommunication link with the radio network 350. The radio network mayinclude base stations or nodeB's providing a radio communication linkwith the mobile stations. The network may also include radio networkcontrollers for controlling the base stations. Furthermore, the networkmay include functionality for providing data communication with externalnetworks, such as the Internet or PSTN (Public Switched TelephonyNetwork) networks, for instance. In FIG. 3, the radio network has beenillustrated as one entity and the exact division of functionalitybetween the base stations and the base station controllers, forinstance, has not been shown. The embodiments of the invention maycorrespondingly be implemented at least partly distributed over variousnetwork elements. Some of the functionality may be implemented in basestations, and some in a base station controller, for instance.

The radio network includes a controller CNTL 300 for coordinating andcontrolling the functionality in the network. The network includescontrol resources, such as control channel resources CNTL RES 306 andcommunication resources such as user data resources DATA RES 308. Thecontroller may be responsible for providing radio communication usingthe communication and control resources.

The user data resources may be shared channel resources, for instance,defined by a frequency-time combination. Alternatively, the user dataresources may be identified by OSVF code and time combination, forinstance. The control channel resources may be applicable to indicationof the allocation of the user data resources, such as to indicate whichfrequency-time combination, for instance, has been allocated for a user.

In addition to the resource assignment, the control channel signalingmay also indicate the used modulation and coding scheme (MCS), mobilestation identity, and the duration of the resource assignment, forinstance.

The radio network may also include a table or a database for storingmobile station identities belonging to the dynamic allocation DYN 302and the persistent allocation PERS 304. Dynamically allocated 302 mobilestations may use the control channel resources 306 and user dataresources 308. Persistently allocated 304 mobile stations may use theuser data resources 308 for user data transmission/reception, and boththe control channel resources 306 and user data resources 308 for datapacket retransmissions.

The radio network may also include an allocator and reallocator REALLOC310 for coordinating initial allocation and reallocation of mobilestations. Reallocation means allocating dynamically allocated userspersistently and vice versa.

The allocator may allocate mobile stations to use at least one of adynamic allocation and a persistent allocation, each allocation defininga different utilization of the control resources and communicationresources. A mobile station may use one of the allocations, or both ofthem. A mobile station may use both of the allocations when a mobilestation is persistently allocated but uses dynamic allocation forretransmissions, for instance. Different utilization of communicationresources and control resources means, for instance that in the dynamicallocation the allocated communication resource is indicated for eachTTI, whereas in the persistent allocation no indication of thecommunication resource on the control channel is needed during use ofthe communication resource.

The reallocator 310 may be connected to the dynamic and persistentgroups 302, 304 and include a monitor configured to monitor if areallocation condition associated with these groups is fulfilled. Areallocation condition may be, with respect to the dynamic group, ifthere is a shortage of CCE's, for instance. A threshold value may beprovided for occupied CCE's, and if the number of occupied CCE's exceedsthe threshold value, the reallocation condition is considered fulfilled.Alternatively, the reallocation condition may be the number of freeCCE's. If the number of free CCE's drops below the reallocationcondition, the reallocation condition is considered fulfilled. Withrespect to the persistent allocation, a reallocation condition may bethe number of occupied/free PRB's. The reallocation condition isfulfilled when the number of PRB's is above/below the reallocationconditions.

The network may further include a sorting unit SORT D 312 for sortingthe mobile stations in the dynamic group 302. The mobile stations may besorted in a descending order, for instance, according to a predefinedmetric. Calculations for the metric may be provided in the calculationunit METR D→P 316. In an embodiment, the metric takes into account, foreach mobile station, only the condition in the destination group, thatis the persistent group. In another embodiment, the metric takes intoaccount only the condition in the originating group, that is the dynamicgroup.

When considering reallocation from the dynamic group to the persistentgroup, the reallocator 310 may also check if there are sufficientlyresources in the persistent allocation to serve the mobile station(s).

The reallocator 310 may perform the reallocation iteratively. First, thehighest priority mobile station that is the first in the sorted listkept in 312 is considered. If the persistent group has enough resourcesto serve the first mobile station, it is reallocated to the persistentgroup. In the reallocation, the control channel may provide one bit, forinstance, to indicate that the communication resource indicated by thecontrol channel is persistently allocated until it is released. Themobile station may itself notice release of the persistent allocation,or the network may indicate it to the mobile station by signaling, forinstance. In this reallocation, the CCE(s) used by the first mobilestation are released, and a persistent resource is reserved from thepool of user data resources 308. If the reallocation condition is nolonger fulfilled, the reallocation process may be stopped. However, ifthe reallocation condition is still in force, the process may proceed tothe second mobile station in the sorted list. This may continue untilthe reallocation condition is no longer fulfilled. If the destinationallocation is incapable of serving a certain mobile station, this mobilestation may be skipped.

The network may further include a sorting unit SORT P 314 for sortingthe mobile stations in the persistent group 302. The mobile stations maybe sorted in a descending order, for instance, according to a predefinedmetric. Calculations for the metric may be provided in the calculationunit METR P→D 318. In an embodiment, the metric takes into account, foreach mobile station, only the condition in the destination group, thatis, the dynamic group. In another embodiment, the metric takes intoaccount only the condition in the originating group, that is, thepersistent group. In still another embodiment, the metric takes intoaccount the condition in the originating group and in the destinationgroup. For instance, the metric may take into account the savings in thepersistent group and the cost in the dynamic group if the mobile stationis to be reallocated.

When considering reallocation from the persistent group to the dynamicgroup, the reallocation unit may also check if there are sufficientlyresources in the dynamic allocation to serve the mobile station(s).

The reallocation unit 310 may perform the reallocation iteratively.First, the highest priority mobile station that is the first in thesorted list kept in 314 is considered. If the dynamic allocation hasenough resources to serve the first mobile station, it is reallocatedaccording to the dynamic allocation. In this reallocation, thepersistently allocated resources used by the first mobile station arefreed, and a control channel resource is reserved from the pool ofcontrol channel resources 306. If the reallocation condition is no morefulfilled, the process may be stopped. However, if the reallocationcondition is still in force, the process may be continued to the secondmobile station in the sorted list. This may be continued until thereallocation condition is no more fulfilled. In the event thedestination allocation is not capable of serving a certain mobilestation, this mobile station may be skipped.

The network may further include a communication unit 320 for providingradio communication links towards the mobile stations, and other neededcommunication interfaces, such as those towards connected data networks.

FIG. 3 shows two mobile stations 330 and 340 having a bi-directionalradio communication link with the network 350. The mobile station 330has been illustrated more in detail with respect to the functionalitydisclosed in the above embodiments. The mobile station may include anentity DYN 334 for coordinating participation in the dynamic allocation.That is, the mobile station may read from a control channel a referenceto the user data resource, and use the indicated user data resource foruser data communication. The mobile station may also include an entityPERS 336 for coordinating participation in the persistent allocation.Then, the mobile station may use a persistently allocated resource foruser data communication, and use dynamic allocation only forretransmission and SID communication, for instance. For radiocommunication of the mobile station, a transceiver 332 is provided.

In an embodiment, an apparatus may be provided, which apparatus may be achip, a processor, a base station, a base station controller or someother network element, for instance. In an embodiment, the communicationresources are shared channel resources defined by a combination offrequency and time, and the control resources are control channelresources configured to indicate the frequency-time combinationallocated to a mobile station on the shared channel. That is, thecontrol channel resources may indicate which shared channel resource isallocated to a particular mobile station. The resource may be an uplinkor a downlink resource.

In an embodiment, the allocator may be configured to allocate to amobile station, in the dynamic allocation, at least one control resourceand a dynamic communication resource indicated by the control resource.Dynamically allocated mobile stations may thus use both control andcommunication resources. The communication resource may be different foreach communication frame, for instance.

The allocator may be configured to allocate in the persistent allocationthe same communication resource to a mobile station in at least twosuccessive radio frames without continuous associated control resourceallocation. Thus, in the persistent allocation, there may be no need forallocation of control resources. Initially, the indication of thepersistent communication resource may be provided on the controlchannel, but there after the control resource may be released and themobile station may continue communication on the user data channelwithout any associated control resource.

The reallocation condition associated with the dynamic group may be thenumber of reserved control resources exceeding a predetermined thresholdvalue. Alternatively, the number of available resources may fall under apredetermined threshold value. In such cases, the reallocator isconfigured to allocate, if the reallocation condition is fulfilled, atleast one mobile station from the dynamic allocation to the persistentallocation.

The reallocation condition associated with the persistent group may bethe number of reserved communication resources exceeding a predeterminedthreshold value. Alternatively, the number of available resources mayfall under a predetermined threshold value. The reallocator may then beconfigured to allocate, if the reallocation condition is fulfilled, anallocation of at least one mobile station from the persistent allocationto the dynamic allocation.

The reallocator may be configured to reallocate a mobile station whosereallocation optimises a reallocation metric for optimizing one or moreof savings to an allocation, which the mobile station is moved from, andcost to an allocation which the mobile station is moved to. Thereallocation metric may be in the form of a cost function, where boththe condition in the originating pool (which the mobile station is movedfrom) and the destination pool (which the mobile station is moved to)may be taken into account.

The reallocator may be configured to sort the mobile stations into anorder of priority according to the reallocation metric, reallocate amobile station having as high a priority as possible and being able tobe served in the allocation which the mobile station would be moved to,and repeat reallocating mobile stations in the order of priority as longas the reallocation condition is no more fulfilled. Thus, if areallocation condition is fulfilled, one or more mobile stations may bereallocated. Reallocations may be carried out as long as thereallocation condition is no more fulfilled, for instance. For thereallocations, the mobile stations may be sorted in an order of prioritysuch as superiority according to the metric. Moving of the highestpriority user may first be considered. In the destination groups hasenough resources the serve the highest priority user, it is moved. Ifnot, the next highest user is considered and so on.

The reallocator may be configured to reallocate from the dynamicallocation to the persistent allocation a mobile station having atalk-spurt beginning or ongoing. Beginning of a talk-spurt may be anindication that the user may need the resource for some while. In such acase, a persistent allocation may be suitable.

The allocator may be configured to allocate mobile stations startingcommunication or becoming active according to the dynamic allocation. Itis feasible to first allocate a user dynamically and then, if need be,reallocate it later on persistently.

A method and a computer program product implementing the method andcarrying out the functionality of the apparatus may be provided. Theembodiments may be implemented by software, hardware, or a combinationthereof. The embodiments may be implemented on one or more processorsusable in base stations or base station controllers, for instance. Thedisclosed functionality in various embodiments may be implemented by wayof a computer program product encoding a computer program ofinstructions for executing a computer process of the above-describedmethod. The computer program product may be implemented on a computerprogram distribution medium. The computer program distribution mediummay be any of the known ways of distributing software, such as acomputer readable medium, a program storage medium, a record medium, acomputer readable memory, a computer readable software distributionpackage, a computer readable signal, a computer readabletelecommunication signal, and a computer readable compressed softwarepackage. Alternatively, some of the functionality may be implemented byhardware, such as ASIC (Application Specific Integrated Circuit) or by acombination of hardware and software.

It will be obvious to a person skilled in the art that, as technologyadvances, the inventive concept can be implemented in various ways. Theinvention and its embodiments are not limited to the examples describedabove but may vary within the scope of the claims.

The invention claimed is:
 1. An apparatus comprising at least oneprocessor and at least one memory including computer programinstructions, the at least one memory and the computer programinstructions configured to, with the at least one processor, direct theapparatus at least to: control radio communication using communicationresources for user data communication and control resources to indicateassignment of the communication resources; cause allocation of mobilestations to use at least one of a dynamic allocation and a persistentallocation, wherein each allocation defines a different utilization ofthe control resources and the communication resources in a radio system;cause monitoring of one or more reallocation conditions associated withat least one of the dynamic allocation and the persistent allocation;and cause reallocation of at least one mobile station in an instance inwhich at least one of the one or more reallocation conditions isfulfilled; wherein the reallocation condition associated with thepersistent allocation is a number of reserved communication resources inthe radio system exceeding a predetermined threshold value, thepredetermined threshold value being based on system performance, andwherein the apparatus is further directed to cause reallocation, in aninstance in which the reallocation condition associated with thepersistent allocation is fulfilled, of at least one of the mobilestations from the persistent allocation to the dynamic allocation. 2.The apparatus according to claim 1, wherein the communication resourcesare shared data channel resources, and the control resources are controlchannel resources configured to indicate the communication resourceassignment allocated to one of the mobile stations on a shared datachannel.
 3. The apparatus according to claim 1, wherein the apparatus isfurther directed to cause allocation, to at least one of the mobilestations in the dynamic allocation, of at least one control resource anda dynamic communication resource indicated by the control resource. 4.The apparatus according to claim 1, wherein the apparatus is furtherdirected to cause allocation, in the persistent allocation, of the samecommunication resource to at least one of the mobile stations withoutassociated control resource allocation during use of the allocatedcommunication resource.
 5. The apparatus according to claim 1, whereinthe reallocation condition associated with the dynamic allocation is anumber of reserved control resources exceeding a predetermined thresholdvalue and wherein the apparatus is further directed to causereallocation, in an instance in which the reallocation conditionassociated with the dynamic allocation is fulfilled, of at least one ofthe mobile stations from the dynamic allocation to the persistentallocation.
 6. The apparatus according to claim 1, wherein the apparatusis further directed to cause reallocation of at least one of the mobilestations, the reallocation optimizing a reallocation metric to optimizeat least one of savings to an allocation that the at least one mobilestation is moved from, and cost to an allocation that the at least oneof the mobile stations is moved to.
 7. The apparatus according to claim6, wherein the apparatus is further directed to: sort the mobilestations in order of priority according to the reallocation metric;cause reallocation of at least one of the mobile stations to anallocation having as high a priority as possible and being able to beserved in the allocation that the at least one mobile station would bemoved to; and cause repeated reallocation of the mobile stations in theorder of priority until the reallocation condition is no longerfulfilled.
 8. The apparatus according to claim 1, wherein the apparatusis further directed to cause reallocation, from the dynamic allocationto the persistent allocation, of one of the mobile stations having atalk-spurt beginning or ongoing.
 9. The apparatus according to claim 1,wherein the apparatus is further directed to cause allocation of themobile stations starting communication or having a talk-spurt beginningaccording to the dynamic allocation.
 10. An apparatus comprising:controlling means for controlling radio communication usingcommunication resources for user data communication and controlresources to indicate allocation of the communication resources;allocating means for causing allocation of mobile stations to use atleast one of a dynamic allocation and a persistent allocation, whereineach allocation defines a different utilization of the control resourcesand the communication resources in a radio system; monitoring means forcausing monitoring of one or more reallocation conditions associatedwith at least one of the dynamic allocation and the persistentallocation; and reallocating means for causing reallocation of at leastone mobile station in an instance in which at least one of the one ormore reallocation conditions is fulfilled; wherein the reallocationcondition associated with the persistent allocation is a number ofreserved communication resources in the radio system exceeding apredetermined threshold value, the predetermined threshold value beingbased on system performance, and wherein the apparatus further comprisesmeans for causing reallocation, in an instance in which the reallocationcondition associated with the persistent allocation is fulfilled, of atleast one of the mobile stations from the persistent allocation to thedynamic allocation.
 11. The apparatus according to claim 10, wherein thereallocation condition associated with the dynamic allocation is anumber of reserved control resources exceeding a predetermined thresholdvalue, and wherein the reallocating means causes reallocation, in aninstance in which the reallocation condition associated with the dynamicallocation is fulfilled, of at least one mobile station from the dynamicallocation to the persistent allocation.
 12. A method, comprising:controlling radio communication using communication resources for userdata communication and control resources to indicate allocation of thecommunication resources; causing allocating of mobile stations to use atleast one of a dynamic allocation and a persistent allocation, whereineach allocation defines a different utilization of the control resourcesand the communication resources in a radio system; causing monitoring ofone or more reallocation conditions associated with at least one of thedynamic allocation or the persistent allocation; and causingreallocating of at least one mobile station in an instance in which atleast one of the one or more reallocation conditions is fulfilled;wherein the reallocation condition associated with the persistentallocation is a number of reserved communication resources in the radiosystem exceeding a predetermined threshold value, the predeterminedthreshold value being based on system performance, and wherein themethod further comprises causing reallocating, in an instance in whichthe reallocation condition associated with the persistent allocation isfulfilled, of at least one of the mobile stations from the persistentallocation to the dynamic allocation.
 13. The method according to claim12, wherein the communication resources are shared data channelresources, and the control resources are control channel resourcesindicating the communication resource assignment allocated to one of themobile stations on a shared data channel.
 14. The method according toclaim 12, wherein in the dynamic allocation of at least one controlresource and a dynamic communication resource indicated by the controlresource is allocated to one of the mobile stations.
 15. The methodaccording to claim 12, wherein in the persistent allocation, the samecommunication resource is allocated to one of the mobile stationswithout associated control resource assignment during use of thecommunication resource.
 16. The method according to claim 12, wherein areallocation condition associated with the dynamic allocation is anumber of reserved control resources exceeds a predetermined thresholdvalue, and wherein causing reallocating further comprises causingreallocating, in an instance in which the reallocation conditionassociated with the dynamic allocation is fulfilled, of at least onemobile station from the dynamic allocation to the persistent allocation.17. The method according to claim 12, wherein causing reallocatingfurther comprises causing reallocating of one of the mobile stations,the reallocation optimizing a reallocation metric to optimize at leastone of savings to an allocation that the one of the mobile stations ismoved from, and cost to an allocation that the one of the mobilestations is moved to.
 18. The method according to claims 17, whereincausing reallocating further comprises: sorting the mobile stations inorder of priority according to the reallocation metric; causingreallocating of one of the mobile stations to an allocation having ashigh a priority as possible and that would be able to be served in theallocation that the one of the mobile stations would be moved to; andcausing repeated reallocating of the mobile stations in the order ofpriority until the reallocation condition is no longer fulfilled. 19.The method according to claim 12, wherein causing reallocating furthercomprises causing reallocating, from the dynamic allocation to thepersistent allocation, of one of the mobile stations having a talk-spurtbeginning or ongoing.
 20. The method according to claim 12, whereincausing allocating comprises causing allocating of the mobile stationsstarting communication or becoming active according to the dynamicallocation.
 21. A computer-readable non-transitory storage mediumencoded with instructions that, when executed by a computer, perform aprocess, the process comprising: controlling radio communication usingcommunication resources for user data communication and controlresources to indicate allocation of the communication resources; causingallocation of mobile stations to use at least one of a dynamicallocation and a persistent allocation, wherein each allocation definesa different utilization of the control resources and the communicationresources in a radio system; causing monitoring of one or morereallocation conditions associated with at least one of the dynamicallocation or the persistent allocation; and causing reallocating of atleast one mobile station in an instance in which at least one of the oneor more reallocation conditions is fulfilled; wherein the reallocationcondition associated with the persistent allocation is a number ofreserved communication resources in the radio system exceeding apredetermined threshold value, the predetermined threshold value beingbased on system performance, and wherein the process further comprisescausing reallocating, in an instance in which the reallocation conditionassociated with the persistent allocation is fulfilled, of at least oneof the mobile stations from the persistent allocation to the dynamicallocation.
 22. The computer-readable storage medium according to claim21, wherein a reallocation condition associated with the dynamicallocation is a number of reserved control resources exceeding apredetermined threshold value, and wherein causing reallocating furthercomprises causing reallocating, in an instance in which the reallocationcondition associated with the dynamic allocation is fulfilled, of atleast one mobile station from the dynamic allocation to the persistentallocation.